The present invention relates to a throttle valve control device for an internal combustion engine of an automobile, and more particularly to a motor-driven throttle valve control device for the automobile having an auto-drive function to keep a running speed constant.
Conventionally, a motor-driven throttle valve control device for an internal combustion engine is disclosed in Japanese Patent Laid-open Publication No. 63-140832, for example. In this conventional device, an upper limit of an opening angle of a throttle valve adjustable by a motor is restricted by a mechanical device connected to an accelerator pedal to be operated by an operator. Since the opening angle of the throttle shaft may be suitably adjusted by the motor, the internal combustion engine may be controlled in accordance with the running condition of the automobile. Further, since the maximum opening angle is defined by the mechanical device, the uncontrollable situation of the engine may be avoided. However, this device cannot effect auto-drive control for keeping the running speed constant wherein the throttle valve is adjusted by an actuator without the operation of the accelerator pedal by the operator.